1. Field of the Invention
This invention relates to the aerial refueling of unmanned vehicles and more particularly to a system for such aerial refueling which is completely automated.
2. Description of the Related Art
The use of unmanned air vehicles for combat related missions as well as reconnaissance missions is extensively employed by the military. Effective refueling systems, however, for unmanned aircraft are not known to be available.
Aerial refueling systems are used extensively to extend the range of manned vehicles. Such systems generally employ either what is known as the flying boom or the hose and drogue. With the flying boom, a fueling boom is lowered and extended from the aft fuselage of the tanker aircraft by a boom operator. The boom operator then steers the boom into the fuel receptacle of the aircraft to be refueled. In the hose-and-drogue system, a paradrogue attached to a hose is generally employed. The hose is wrapped around a drum or hose reel and deployed by the tanker aircraft crew by means of a hose reel drive mechanism. This drive mechanism is powered independently by the tanker aircraft power supply or by means of a ram air turbine. The aircraft being refueled has either a fixed or retractable probe and the pilot of this aircraft flies the probe into the drogue. Hose-and-drogue systems can be deployed from the aircraft fuselage or from pods mounted on the fuselage.
Hose-and drogue systems have advantages over flying boom systems in that they can service several aircraft simultaneously from units installed in wing mounted pods as well as fuselage mounted hoses. The flying boom, on the other hand can only service one aircraft at a time. Also the hogue-and-drogue systems can refuel both fixed wing and rotary wing aircraft while the flying boom can only service fixed wing aircraft.
Refueling systems of the prior art are not suitable for refueling unmanned aircraft and certainly not suitable for refueling from an unmanned tanker aircraft. The system of the present invention is an improvement over the prior art in that it provides an automatic aerial refueling system capable of refueling unmanned air vehicles from either manned or unmanned tanker aircraft.
The system of the present invention uses a DC motor with a variable speed controller or a controlled hydraulic drive system for driving a hose reel around which the hose through which fuel is fed to the drogue is wound. The controller for the hose reel incorporates a radio transponder and antenna. The aircraft to be fueled has a similar transponder and antenna. The tanker transponder initiates communications with the transponder of the aircraft to be refueled to provide control signals which are employed to reduce the relative motion between the two aircraft. A lidar tracker with a miniature video camera maintains a line of sight between the tanker drogue and the probe of the aircraft to be refueled. In this manner, the drogue and probe are brought into contact with each other and maintained in such contact.
Drogue motion resulting from aerodynamic forces and the structural response of the hose is controlled either by a lifting surface control system mounted on the paradrogue base and deployed by means of powered actuators or a thrust vector control system consisting of multiple thrust nozzles mounted radially on the drogue base which are powered by a suitable power source.
It is therefore an object of this invention to provide an improved aerial fueling system which can be employed with unmanned aircraft.
It is a further object of this invention to enable the fueling of an unmanned aircraft by an unmanned tanker.
Other objects of the invention will become apparent in view of the following description taken in connection with the accompanying drawings.